JPH01319044A - Photoconductive image forming member containing electron transferring polysilirene - Google Patents

Abstract

PURPOSE: To ensure chemical and electrical stabilities by successively forming an electron transferring layer made of a specified polysilylene, a metal oxide layer and a light excitation layer contg. amorphous hydrogenated silicon on a substrate. CONSTITUTION: An adhesive blocking layer 4 as an optional layer, an electron transferring layer 5 made of a polysilylene represented by formula I, an SiO2 layer 7 and a light excitation layer 9 for electric charge carriers contg. amorphous hydrogenated silicon contg. about 10-30atm% hydrogen are successively formed on a substrate 3. In the formula I, each of R1 -R6 is an alkyl, an aryl, a substd. alkyl, substd. aryl or alkoxy, (m), (n) and (p) show the percentages of specified monomeric units of the entire polymer and n+m+p=100%. Chemical and electrical stabilities can be ensured.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates generally to photoconductive imaging members comprising electron transporting polysilylene.

More particularly, in one embodiment, the present invention provides photoexcitable layers of hydrogenated or halogenated amorphous silicon, electron transport layers comprising polysilylene as disclosed in U.S. Pat. No. 4,618,551; (the entire disclosure of which is incorporated herein by reference), and a metal oxide layer disposed therebetween. In one particular embodiment of the invention, the imaging member comprises a supporting substrate, a hydrogenated amorphous silicon photoexcitable layer, polysilylene, particularly poly(methylphenyl)silylene, poly(n
-propylmethyl)silylene and other similar silylene, and a metal oxide layer comprising silicon oxide disposed between the electron transport layer and the photoexcitation layer.

The photoconductive imaging members of this invention are particularly useful in electrophotography, especially electrostatography, including methods that employ liquid ink compositions for development. Additionally, the imaging members of the present invention are chemically and electrically stable and can be used in electrophotographic imaging equipment for extended periods of time.

[Conventional technology]

Imaging members containing polysilylene are disclosed in U.S. Patent No. 4.618.
．． No. 551. More particularly, the US patent discloses polysilylene tag transfer compounds for use in double layered imaging members as set forth in claim 1.

[Purpose of the invention]

It is an object of the present invention to provide a photoconductive imaging member having the advantages mentioned above.

[Disclosure of the invention]

These and other objects of the present invention are achieved by providing a photoconductive imaging member comprising an electron transporting polysilylene. More particularly, according to the invention, a hydrogenated or halogenated amorphous silicon photoexcitable layer;
individually selected from the group consisting of alkyl, aryl, substituted alkyl, substituted aryl and alkoxy; m, n,
and p is a number indicating the proportion of each specific monomer unit in the entire polymer, and the total of rl + m + p is 100%
and a metal oxide, such as silicon oxide, disposed therebetween. The above formula % formula % and θ%≦p≦100%. Any of the monomer units of the polysilylene may be randomly distributed throughout the polymer or may alternate in blocks of variable length.

Illustrative specific examples of polysilylene electron transport compounds that can be used in the photoconductive imaging members of this invention include poly(methylphenylsilylene), poly(methylphenylsilylene-codimethorsilylene), poly(cyclohexylmethylsilylene) ), poly(tert-butylmethylsilylene), poly(phenylethylsilylene), poly(n-propylmethylsilylene), poly(
p-)lylmethylsilylene), poly(cyclotrimethylsilylene), poly(cyclotetramethylenesilylene), poly(cyclopentamethylenesilylene), poly(
di-t-butylsilylene-cozymethylsilylene),
Poly(diphenylsilylene-cophenylmethylsilylene), poly(cyanoethylmethylsilylene), poly(phenylmethylsilylene), etc. Preferred electron transporting polysilylenes for use in the imaging members of the present invention include poly(methylphenyl)silylene, poly(cyclohexylmethyl)silylene and poly(phenethylmethyl)silylene.

This layer preferably has a thickness of about 4 to about 25 microns. While not wishing to be bound by theory, it is believed that the polysilylene functions as an electron transporter because charges excited in the amorphous silicon layer are injected into the polysilylene through the oxide layer. Polysilylene therefore acts as an electron transport medium.

Further, in the imaging member of the present invention, the charge photoexcitation layer preferably comprises hydrogenated amorphous silicon or doped hydrogenated amorphous silicon in which the dopant is a halogen material. In yet another embodiment, this layer is protected or electrically stabilized by a thin layer of silicon nitride, silicon carbide or hydrogenated amorphous carbon thereon. moreover,
The thickness of this layer is preferably from about 0.5 to about 3 microns, more preferably 1.5 microns. The above protective layer is
It is generally not used when the polysilylene charge transport layer is between the supporting substrate and the photoexcitation layer.

Examples of metal oxide layers, typically present at a thickness of about 0.1 to about 5 microns, include silicon oxide, tin oxide, germanium oxide, and the like. Other layer thicknesses can be used as long as the objectives of the invention are achieved.

The photoconductive imaging members of this invention can be made by many known methods, the process parameters and the order of coating each layer depending on the desired member. For example, the members of the present invention may be prepared by providing a conductive substrate having an optional tag blocking layer and an optional adhesive layer, and applying an electrolyte to the substrate by solvent coating, laminate coating, or other methods. It can be made by applying a transport polysilylene layer, a metal oxide layer and a photoexcitation layer. Other methods include melt extrusion, dip coating and spraying.

In one particular embodiment, a supporting substrate such as aluminum is provided. The electron transport polysilylene layer is then applied from the solution, which may be done by any number of known methods, such as spread coating, dip coating, etc. Generally, the solution is benzene, After drying and removing the solvent, the resulting device was placed in a plasma reactor (PECVD-plasma) for the purpose of adding a metal oxide layer. accelerated chemical vapor deposition). In this method, silane gas, pure or containing oxygen, nitrogen or carbon-containing gases, or optionally doped, is decomposed in an electrical discharge into cohesive radicals that bind to the growing film. The decomposition temperature is approximately 2
00°C to about 250°C, although other temperatures outside these ranges can be used so long as the objectives of the invention are achieved. The dopant is phosphorus or diborane in an amount of about 1 to about 20 ppIl, preferably 10 ppm. An optional overcoating can then also be applied, for example by PECVD, such as using an ammonia gas and silane mixture as a silicon nitride overcoat.

Overcoatings for these components can include silicon nitride, amorphous carbon, silicon carbide, and the like, and these overcoatings can be applied at a thickness of about 0.1 to about 5 microns. These overcoatings are applied by known plasma enhanced chemical vapor deposition techniques.

In order to more clearly understand the present invention and its features, various embodiments will be described below with reference to the drawings.

1, a supporting substrate 3, an optional adhesion blocking layer 4, a polysilylene electron transport layer 5, a silicon oxide layer 7, and a hydrogenated amorphous silicon component containing from about 10 to about 30 atomic percent hydrogen. Illustrated is a negatively charged photosensitive imaging member of the present invention comprising a charge carrier photoexcitable layer 9 comprising:

In FIG. 2, a conductive support substrate 15 of aluminized Mylar, an electron transport layer 17 comprising poly(methylphenylsilylene) 19 having a preferred thickness of about 10 microns, and a carbon dioxide layer 17 having a preferred thickness of 0.1 microns are shown. A negatively charged photoconductive imaging member of the present invention comprises a silicon layer 21 and a photoexcitable layer 23 comprising hydrogenated amorphous silicon containing about 20 atomic percent hydrogen and having a preferred thickness of 0.5 microns. Illustrated. The photoexcitation and electron transport components may be dispersed in an inert resin binder such as polyester, polycarbonate, or the like.

Also within the scope of this invention are forming members, such as imaging members, which can employ protective overcoating layers such as silicon carbide and silicon nitride at preferred thicknesses of about 1 to about 2 microns.

Further, for the imaging members of the present invention, the supporting substrate layer may be opaque or substantially transparent and may include any suitable material having predetermined mechanical properties. That is, these substrates include a layer of non-conductive material such as an inorganic or organic polymeric material, a layer of organic or inorganic material with a conductive surface layer,
Or it may include a layer of conductive material such as, for example, aluminum, chromium, nickel, indium, tin oxide, brass, and the like.

The substrate can be flexible or rigid, for example a plate,
It can have any of a number of different shapes, such as a cylindrical drum, a scroll, an endless flexible belt, etc. Preferably,
The substrate is in the form of an endo-flexible belt. The thickness of the substrate layer depends on many factors, including economics. That is, the substrate layer may have a substantial thickness of, for example, 100 mils (2.54 mm);
Alternatively, it may be the minimum thickness that does not adversely affect the imaging member. In preferred embodiments, the thickness of this layer ranges from about 3 to about 10 mils (76.2-254 μm).

An example of a photoexcitable moiety is hydrogenated or halogenated amorphous silicon containing about 10 to about 30, preferably about 25 to about 40 atomic percent hydrogen or halogen. Generally, it is desirable to prepare this layer at a thickness sufficient to absorb about 90% or more of the radiation applied to the layer during the imaging exposure step. The maximum thickness of this layer depends primarily on factors such as mechanical considerations, such as whether a flexible photosensitive imaging member is desired. Generally, however, this layer has a thickness of about 1 to about 25 microns, preferably about 4 to about 25 microns.

Optional resin binders for use in the polysilylene layer are described, for example, in U.S. Pat. No. 3.121.006.
Polyesters, such as those disclosed in No.
These include polyvinyl butyral, polyvinyl carbazole, polycarbonate resin, epoxy resin, polyhydroxy ether resin, and the like.

Further, the image forming member of the present invention includes Daichiru (Ditel).
Adhesive layers may also be included, such as polyesters available as ) PH-100, Daichill PH-200, and Daichill PFI-222 (all available from Goodyear Tire and Rubber Co.); polyvinyl butyral; DuPont 49.000 polyester.

This adhesive layer generally has a thickness of about 200 to about 900 μm and is applied, for example, from a solution of tetrahydrofuran, toluene and methylene chloride. The adhesive layer may be present on the supporting substrate or between the optional hole blocking layer and the supporting substrate. Examples of blocking layers include siloxanes such as those disclosed in U.S. Pat. No. 4,464,450. Other blocking layers include U.S. Pat.
, 033 and 4.291.110, including (gamma-aminopropyl)methyljethoxysilylene.

The imaging members of the present invention are useful in a variety of electrophotographic imaging systems, particularly those in which an electrostatic image is formed on a photosensitive imaging member and a toner composition comprising resin particles and pigment particles (e.g.
U.S. Pat. No. 4,558.108, No. i, 298.6
No. 72 and No. 4.569,635)
It is useful in an electrostatographic system that involves developing the image by a method of developing the image, then transferring the developed image to a suitable substrate and fusing the resulting image.

More specifically, the surface of the photoreceptor described above is uniformly charged to the desired polarity using a corona charging device common in electrophotographic practice. Thereafter, the charged photoreceptor is imagewise exposed to light at a wavelength that is substantially entirely absorbed by its charge excitation layer.

The excited charge carriers in the excitation layer are separated by the electric field in such a way that the positive carriers are transferred to the negatively charged surface, while the negative charge carriers, electrons, are transferred to the positive or grounded electrode (substrate). In this method, an electrostatic latent image is formed and developed and transferred to a substrate material, such as paper, in subsequent steps.

The transferred image is then fused to the substrate using heat or pressure, or a combination thereof.

In the multilayer photoreceptor described above, it is important that electrons be injected into the transport layer with high efficiency and transported through the transport layer without losses due to trapping (resulting in the accumulation of residual charge). Residual charge will give poor quality to the resulting image. It is also important that the transport of electrons through the transport layer be rapid with respect to subsequent processing in the copying device. For example, after exposure, charge transfer should be substantially complete before subjecting the latent image to a development process (which converts the electrostatic latent image into a visible image). If transport still occurs during development, poor images will be obtained. In the imaging member of the present invention, this problem is substantially reduced.

The polysilylene electron transport polymer of the present invention has several advantages when used in photoreceptor devices. for example,
These polymers can be efficient with photoexcitable materials having high efficiency in excitation of electrons. Electron transport could increase design flexibility in relation to surface charging and development. For example, if a negative toner and positive surface charge were desired, the device could be fabricated with a photoexcitable layer on a substrate overcoated with an electron transport layer. Electrons excited in the charge excitation layer and transported through the charge transport layer will neutralize the positive surface charge in an image-forming manner to generate an electrostatic latent image. This latent image can then be developed with the desired negative toner.

〔Example〕

Example 1 Poly(methylphenyl)silylene having a weight average molecular weight of 900,000 is deposited from a 2% solution in toluene by a known draw bar coating method onto an aluminum substrate having a thickness of approximately 3 mils (>76.2 μm). A photosensitive imaging member was prepared by coating. After drying, this layer had a thickness of about 10 microns. The polysilylene layer was then coated with 0.1 µm of silicon oxide by draw coating. A layer of hydrogenated amorphous silicon containing 20 atomic % hydrogen and having a thickness of 0.5 microns was applied, followed by an overcoating layer of silicon nitride (SiN, It was applied in

Example 2 A photosensitive imaging member was prepared by repeating the procedure of Example 1, but substituting poly(cyclohexylmethyl)silylene having a weight average molecular weight of 1750.000 for the poly(methylphenyl)silylene described above. , this layer was coated from a 30% solution in toluene.

Example 3 A photosensitive imaging member was prepared by repeating the procedure of Example 1, but with a weight average molecular weight of 1 soo, oo.

Poly(phenethylmethyl)silylene having the following formula was used in place of the poly(methylphenyl)silylene described above, and the coating was made from a 40% solution of Tolu 179. moreover,
The thickness of each layer was 8 microns for poly(phenethylmethyl)silylene, 0.1 micron for silicon oxide, 0.5 micron for hydrogenated amorphous silicon, and 1.5 microns for silicon nitride.

The photodischarge curve of the imaging member of Example 1 showed excellent contrast potential. Accordingly, high quality images can be produced in an electrostatographic imaging test apparatus incorporating the negatively charged imaging member of Example 1 by forming an image on the imaging member containing known resin particles and pigment particles. is formed by a toner composition containing 88% by weight styrene n-butyl methacrylate resin, 10% by weight carbon black particles, and 2% by weight the charge-promoting additive cetylpyridinium chloride and after development. Probably. Substantially similar results can be obtained with the imaging members of Examples 2 and 3.

Example 4 A photosensitive imaging member was prepared with a 3 mil (76.2 μm) thick aluminized Mylar substrate and coated with 3-aminopropyltriethoxysilane (P.
(available from CR Research Chemicals, Inc.) in ethanol at a wet thickness of 0.5 mil (12.7 μm). After drying for 5 minutes at room temperature and then curing for 10 minutes at 100 °C in a forced air oven, poly(methylphenylsilylene) was applied as an electron transport layer from a solution of toluene and tetrahydrofuran in a 2:1 volume ratio; This was done by a spray method.

After drying, the eyebrows had a thickness of approximately 10 microns.

A photoactive layer of hydrogenated amorphous silicon containing 20 atomic percent hydrogen was then applied to the polysilylene layer using a Bird applicator, and the layer had a thickness of 0.4 microns.

This imaging member was then incorporated into an electrostatographic imaging test system and images with excellent resolution substantially free of background deposits were obtained over a period of over 50,000 imaging cycles.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view of a photoconductive imaging member of the present invention. FIG. 2 is a partial cross-sectional view of another photoconductive imaging member of the present invention.

Claims (1)

Claims: 1. A negatively charged photoconductive imaging member comprising a supporting substrate, a polysilylene electron transport layer, a metal oxide layer, and a photoexcitable layer comprising hydrogenated amorphous silicon on the oxide layer. 2. Polysilylene has the formula: ▲ Numerical formulas, chemical formulas, tables, etc. 2. The imaging member of claim 1, wherein m, n, and p are numbers indicating the proportion of monomer units in the total polymer.